The present invention relates in general to an electron-emission type field-emission display and a method of fabricating the same, and more particular, to a cathode electrode having a configuration that the beeline distance between every surface point of the cathode electrode layer and a gate conductive layer over the cathode electrode is identical.
The invention of carbon nanotube (CNT) has stimulated a novel competition in the development of minimizing nanotechnology globally. Currently, application of the carbon nanotube in optoelectronic display includes carbon-nanotube field-emission display (CNT FED), which is the most potential flat display panel as recognized in the industry. The conventional field-emission display is constructed by a front panel and a substrate, which generates a spike discharge at the cathode spike to emit an electron beam. The electron beam then impinges the phosphor layer coated on the screen to generate image. Such type of display has the characteristics of larger display area, shorter response time, and wider viewing angle. Thereby, it can be broadly applied to electronic products that require flat panel display to replace the conventional cathode ray tube (CRT) screen.
The front panel and the substrate are housed in a vacuum package. A spacer is disposed between the front panel and the substrate to prevent the glass plate from being broken by atmosphere pressure. In the past, the high fabrication cost becomes a bottle neck of the development of the field-emission display. However, the development of carbon nanotube resolves the high-cost issue while the image quality of cathode ray tube is maintained. The carbon nanotube field-emission display also includes the power saving and small-volume features.
However, the current carbon-nanotube field-emission display is still problematic in application. FIG. 1 illustrates conventional field-emission display that includes an anode electrode layer 1a and a cathode electrode layer 2a. The anode electrode layer 1a includes a substrate 11a, a first conductive layer 12a on the substrate 11a, and a second conductive layer 13a covering the second conductive layer 12a. The first and second conductive layers 12a and 13a construct an anode 14a to be impinged by an electron beam from a cathode 26a. The cathode electrode layer 2a includes a substrate 21a, a first conductive layer (silver paste) 24a (silver paste) formed on the substrate 21a and a second conductive layer (carbon nanotube) 25a formed on the first conductive layer 24a. The first and second conductive layers 24a and 25a construct the cathode 26a. A dielectric layer 26a is formed on the substrate 2a around the cathode 26a, and the field-emission display further comprises a gate conductive layer 3a formed on the dielectric layer 22a. The gate conductive layer 3a has a through hole 31a aligned over the cathode 26a. As shown, the beeline distance between the periphery area of the second conductive layer 25a and the gate conductive layer 3a is shorter than that between the central area of the second conductive layer 25a and the gate conductive layer 3a. Therefore, the electric field at the periphery area of the second conductive layer 25a is higher than that of the central area of the second conductive layer 25a. As a result, the electrons drained at the periphery have a density larger than that of the electrons drained at the central area. The distribution of electrons results in a donut-shape electron beam. The non uniform distribution of electrons also results in leakage of electron beams through the gate conductive layer 3a. 